Displays, such as monitors, televisions, projectors, touch screens, or other display devices, consume a large portion of the power used by a typical computing device. For example, some studies have shown that the display can account for as much as 40 percent or more of the total system power consumption, depending on the display type, size, etc. Furthermore, it is becoming more common to have multiple displays connected to a computing device, and these displays are generally becoming larger in size, both of which are factors that further increase energy consumption of computing devices. Additionally, many computing devices are not actively used during a large portion of the time that they are on, even when users are present, and many computing devices are also left running at night and on weekends when the users are not present.
A computing device may include a power management mechanism for automatically controlling power used by displays, hard disk drives, and other components of the computing device. Further, most displays include a compatible power management feature that enables a computing device to turn the display off or reduce the amount of power that the display is using. For example, the power management mechanism of a computing device may turn off the display, dim the display, or place the display in a low power state after a predetermined period of user inactivity. As a result, power consumption of displays can be automatically reduced, which can save a large amount of energy, and thereby provide substantial savings to companies that use a large number of computing devices. For instance, a display placed into a powered-down state might typically consume 1 to 3 watts of power. In contrast, an active liquid crystal display (LCD) monitor might consume 15 to 60 watts of power, while an active cathode ray tube (CRT) display or very large LCD might consume 50 to 100 or more watts of power. However, under many conventional power management systems, the power management settings are set according to a specified period of inactivity, which does not take into consideration variations in actual user activity and behavior.